1. Technical Field
The present invention is directed towards a glass adhesion promoter or composition. More specifically, the invention is directed towards a copolymer useful in a glass binding composition, wherein the copolymer has a carboxyl-functional moiety and a substituted amide, silanol, or amine oxide functional moiety. The copolymer is useful both as a fiberglass binder and in providing protective coatings on glass sheets.
2. Background Information
Fiberglass insulation products generally consist of glass fibers bound together by a polymeric binder. The fibers are bound by spraying an aqueous polymer binder onto matted glass fibers soon after the fibers are formed and while they are still hot. This polymeric binder accumulates at the junctions where the fibers cross each other, holding the fibers together at these points. The heat from the fibers vaporizes most of the water in the binder. The fiberglass binder should be flexible so that the fiberglass product can be compressed for packaging and shipping and later recover to its full vertical dimension when installed.
In the past, fiberglass applications employed phenol-formaldehyde resins in their binder systems. These phenol-formaldehyde compositions provided an excellent product with flexibility. However, due to environmental and safety concerns formaldehyde-free polymeric binder systems were developed as a substitute for the phenol-formaldehyde compositions. These formaldehyde-free binder systems typically involve three parts. One part is a polymer such as a polycarboxyl, polyacid, polyacrylic, or anhydride that can be copolymerized with other ethylenically unsaturated monomers. A second part is a cross-linker that is an active hydrogen compound, such as trihydric alcohol, triethanol amine, beta-hydroxy alkyl amides, or hydroxy alkyl urea. The system can also include a catalyst or accelerator, such as a phosphorous containing compound or a fluoroborate compound. Still, these carboxyl-containing polymers and co-polymers show poor adhesion to glass fibers, resulting in insulation that sags over time.
Accordingly, there is a need for alternative fiberglass binder systems that provide the performance advantages of phenol-formaldehyde resins in a formaldehyde-free system. Further, there is a need for a fiberglass binder composition having good adhesion to glass fibers.
It is known to use a phosphorus-based catalyst for fiberglass sizing formulations. While the phosphorus-based catalysts lower the curing temperature, the addition of inorganic salts such as sodium hypophosphite adversely affect the water uptake of the finished product. While not being bound by theory, the inorganic salts introduced in to the insulation system tend to absorb moisture by a capillary mechanism. Accordingly, there is a need to minimize or even eliminate the inorganic salts (electrolytes) in this system. Additionally, there is a need for a fiberglass binder system and its associated resin(s) having improved water and humidity resistance, and that are not subject to the water absorption problems described above.